The invention relates generally to Computed Tomography (CT) systems, and more particularly, to a CT scintillator array using glass and glass ceramic fiber.
CT systems use scintillator detectors to convert a received X-ray intensity to an electrical signal. The scintillator detector includes a scintillator and a photodiode tightly coupled to each other. Scintillators are materials that emit visible or ultraviolet light after interaction of ionizing radiation such as X-rays. The light thus emitted is detected by the photodetector, and converted to an electrical signal.
Such scintillator detectors in CT systems are arranged in the form of scintillator arrays called packs. The packs are arranged to capture different picture elements (hereinafter referred to as pixels) of the desired scan image. The resolution of the scan image is directly related to the size of the pixels in the packs. For better resolution images, smaller pixels are desired. Hence, very accurate dicing and grinding processes are required to control the size of the pixels within the packs.
This leads to various complications in the fabrication process for such packs. The first challenge is the alignment of the pixels. An accurate gap is useful between pixels to allow the use of a castable or other type of reflector. Also the alignment between the collimator and the pack is desirable. Misalignment with the collimator may cause cross-talk and other things that can generate image artifacts. The specification for misalignment between the collimator and the pack is very limited to maintain acceptable image quality. This limited specification for misalignment leads to thick tungsten plates that reduce the detectors dose efficiency. Tungsten plates eliminate scattered X-rays and thus reduce image noise and increase contrast. The tungsten plates also reduce X-ray punch-through that causes noise in the photodiode and radiation damage. Another challenge is the alignment between the pack and photodiode. Misalignment between the pack and photodiode can cause cross-talk between the pixels. This misalignment can also lead to X-ray generated noise, and radiation damage to the photodiodes.
Due to the stringent fabrication requirements described above, the manufacturing process for the packs becomes expensive. Further, the limitations in the design of these packs restrict the applications areas. For instance, the resolution of the image scanned by a CT system is constrained by the design of the pack used in the CT system.